1. Field of the Invention
The present invention pertains generally to the field of surgical apparatus for opening an anatomic space. More particularly, the present invention pertains to surgical apparatus for use in fascial cleft surgery for tissue dissection wherein a balloon device performs the function of tissue dissection in a minimally invasive manner.
2. Description of the Prior Art
The American Cancer Society estimates that in 2001, 190,000 women were diagnosed with breast cancer. Approximately one in eight women in the U.S. will develop breast cancer in their lifetime. This makes breast cancer the most common cancer among women. These statistics have made breast cancer one of the most pressing issues in women's healthcare today.
The American Society of Plastic Surgeons reports a 174% increase in breast reconstruction procedures between 1992 and 2001, with 81,089 women having reconstructive procedures last year. This trend should increase exponentially as the baby boomer generation matriculates into the high risk age group. In 1998 the Woman's Health and Cancer Rights Act (WHCRA) was passed. This federal law mandates insurance coverage for breast reconstruction following mastectomy. These demographics should make surgical treatment of breast cancer one of the most pressing issues for insurers over the next decade.
The mainstay of breast cancer therapy is surgery. Treatment falls into two categories: 1) breast conservation therapy—consisting of a lumpectomy and axillary node dissection followed by radiation; and 2) Modified radical mastectomy.
Of the roughly 190,000 new cases of breast cancer each year, approximately 100,000 will undergo modified radical mastectomy. Breast reconstruction has long been an option for women who undergo mastectomy. Over the last twenty years this has evolved from a three stage procedure to a one step operation performed at the same time as the mastectomy. Immediate reconstruction at the same time as a skin sparing mastectomy has been referred to as minimally invasive treatment of breast cancer.
Skin Sparing Mastectomy with Immediate Breast Reconstruction
Standard surgical treatments for breast cancer destroy the important connections of the skin of the breast to the chest wall. In addition it leaves a long scar, which covers the entire chest. This creates unnecessary damage that is difficult to reconstruct. Minimally Invasive surgical treatment of breast cancer begins with a skin-sparing mastectomy performed through a circular incision made just outside of the areolar border. In the skin-sparing mastectomy, the skin covering the breast is lifted off the breast tissue, which is removed along with the nipple, areola, and the lymph nodes. The oncologic safety efficacy of skin-sparing mastectomy had been established in the literature with reports such as that by Schusterman out of M. D. Anderson in a report in 1991 from SG&O [The Oncologic Risk of Skin Preservation at Mastectomy When Combined With Immediate Reconstruction of the Breast, Kroll, S. S., Schusterman, M. A. & others. Surgery, Gyn. And Obstetrics, January 1991 Vol. 172, pgs 17-20.]. In this paper the authors described 100 cases of immediate breast reconstruction following skin-sparing mastectomies. In their series, the percentage of local recurrence was 1.2%, which is better than most standard modified radical mastectomy series.
The preservation of the skin covering the breast during mastectomy obviates the need for tissue expanders and thus allows for completion of the reconstruction at the same time as mastectomy. Preservation of the attachment of the breast skin to the chest wall is an important principle of the skin-sparing technique. This is important especially at the inferior and lateral aspect of the breast. It is these attachments of the skin to the chest wall, which give the breast its aesthetic form. Additionally, blood supply through lateral perforators at the lateral aspect of the breast can also be preserved thus insuring the viability of the skin flaps. Removing all of the breast tissue, without going beyond the anatomic boundaries of the breast (and thus destroying the attachment of the skin overlying the breast to the chest wall) becomes the critical factor in this procedure. Understanding of the nature of fascial clefts and their application to breast anatomy is greatly helpful in skin sparing mastectomy.
The breast gland is contained between two layers of superficial fascia. The sub glandular space is in fact a fascial cleft between the superficial fascia on the deep surface of the breast and the deep fascia of the pectoralis major muscle and chest wall. This cleft has anatomic boundaries where all of these layers of fascia fuse and define the limits of the breast. These fusion points have been referred to as the “circum-mammary ligament”. The application of fascial cleft surgery to skin sparing mastectomy performs this critical dissection in a quick, easy and accurate manner. What has yet to be developed, that the present invention provides for, is an instrument specifically designed for performance of fascial cleft surgery in skin sparing mastectomies.
Once the breast specimen has been removed an empty envelope of breast skin remains and requires filling. This can be done in certain patients with autologous tissue in the form of a TRAM (tummy tuck) flap. However, most patients are either poor candidate for this invasive reconstructive surgery or do not desire the lengthy recovery that is associated with it. The majority of patients will opt to fill the void created by the mastectomy with breast implants. Prior to the placement of these implants a muscle flap from the underlying pectoralis major muscle and the latissimus dorsi muscle (from the back), is mobilized to cover the opening created by the mastectomy. The implant is placed under the muscle, which gives a natural softness to the breast and the skin repositioned over it. Following this a full thickness skin graft from the groin is placed on the top of the latissimus flap to reconstruct the areola. The back muscle is removed through an incision which runs horizontally and can be easily hidden by a bra or bathing suite. All this can be performed at the same operation as the mastectomy.
Because the skin overlying the breast and its attachments to the chest wall has been preserved, placement of a breast implant is a relatively straight forward procedure. For this reason it can be performed safely and effectively at the same time as the mastectomy. These procedures are not terribly invasive and do not create a difficult recovery. For this reason patients who are healthy without serious medical conditions can easily have this performed on an outpatient basis (23 hour stay). The use of minimally invasive approaches to mastectomy and immediate reconstruction reduces the number of surgeries required to one. This yields benefits to the patient and their families as well as providers who are responsible for the cost of reconstruction.
The concept of minimally invasive surgery therefore does not require the use of one of the most important tool of the surgical movement—the endoscope. It does however require a surgical philosophy of first doing no unnecessary harm to surrounding anatomic tissues and structures in the process of accomplishing the surgical operational plan. An analogy can be drawn to modern military forces which use smart bombs and high tech equipment to avoid civilian casualties and minimize friendly fire injuries. This often involves the use of small incisions when compared to standard open surgery, but more importantly it minimizes unnecessary dissection that might destroy anatomic form and function leading to prolonged recovery or post operative disability or deformity. Minimally invasive ventral hernia repair illustrates this concept nicely.
Ventral incisional hernias are known to occur following 10% of all laparotomies. Each year 100,000 ventral hernias are repaired in the US (with another 100,000 estimated in the rest of the world). Primary closure has a recurrence rate as high as 50%. This has led to the wide acceptance of repair techniques using synthetic mesh implants as patches to cover abdominal wall defects. This however fails to restore functional strength of the abdominal wall and is still associated with an unacceptably high rate of recurrence (20 to 25% in most series). Mesh repairs have the additional drawback of potential devastating entero-cutaneous fistulas and infections.
The “Components Separation” technique for ventral hernia repair, introduced by plastic surgeon, Oscar Ramirez in 1990, marked a novel approach to this difficult clinical problem. The technique involves wide undermining of the abdominal skin to expose the surface of the anterior abdominal wall, after standard exposure and excision of the hernia sac. Long relaxing incisions are made through anterior fascia one centimeter lateral and parallel to the semi-lunar line. Next, open blunt dissection is performed in a fascial cleft between the layers of the external oblique and internal oblique muscles. Dissection to the borders of this fascial cleft allows for mobilization of the rectus muscles to the midline to achieve direct closure without tension. Midline closure obviates the need for mesh and restores proper function and strength of the anterior abdominal wall.
Despite dramatic reduction in recurrence rates (to single digits in multiple published reports) several factors have prevented widespread adoption of this procedure. First, the vast majority of reports on this technique have been published in the Plastic Surgery literature, while 95% of ventral hernias are performed by general surgeons. Second, the wide undermining of abdominal skin and management of resulting skin excess is outside the comfort zone of most general surgeons. In fact, ischemia of the edges of these skin flaps with resultant wound separation and infection has been the major criticism of the Ramirez technique. Finally, the components separation technique requires more effort and time, than the mesh repair, due to the need for open exposure of the anterior abdominal wall. Endoscopically assisted components separation, reported first by Lowe, Rohrich, et. al. addressed these concerns and has shown it to be a safe and effective method of repair of complicated and recurrent midline ventral hernias (Lowe J B, Garza J R, Bowman J L, Et al. Endoscopically assisted “components separation” for closure of abdominal wall defects. Plast Reconstr Surg 2000; 105:720-29).
The use of Fascial Cleft Surgery allows for quick and easy performance of endoscopically assisted components separation repairs. It alleviates the need for undermining of skin and accomplishes dissection of the abdominal wall components (external oblique and internal oblique muscles), with the new surgical instrument constituting the present invention, to the limits of the fascial cleft. Endoscopy allows for release of the external oblique fascia under direct visualization. This maneuver is performed as quickly and easily as introduction of trocars in laparoscopic procedures. The remainder of the procedure is reduced to direct closure of the midline defect. Attempts by Lowe and others to use existing balloon dissectors based on the Kieturakis prior art failed to dissect the fascial cleft to its anatomic borders due to limitations of its design and the inelastic nature of the balloon. This required multiple insertions of the balloon into the cleft between the external and internal oblique muscles. It also failed to fully dissect the entire anatomic space since dissection was limited to the dimensions of the device. Perhaps this incomplete dissection resulted in insufficient release of tension when the midline was closed and accounts for the higher recurrence of hernia formation in Lowe's endoscopic series when compared to his open components separation repairs. This makes a strong argument for a new improved surgical device for performing minimally invasive ventral hernia repair with fascial cleft dissection.
Minimally Invasive Surgery
Minimally invasive surgery was born in the “fertile crescent” of the peritoneal cavity. Complex surgical maneuvers performed through small incisions are enabled by opening the potential space that is the peritoneal cavity through gas insufflation. Gas is used to inflate the anatomic space until the anatomic boundaries are reached. Once the anatomic potential space has been opened and inflated to its limits an endoscope is inserted and the space is inspected and manipulated as necessary. Minimally invasive procedures outside the peritoneum have defied exploration because of the lack of an easily accessible and inflatable working space.
Bonutti, U.S. Pat. No. 5,163,949, recognized the need for retraction of soft tissues when working outside the peritoneal cavity. He envisioned cannulas and catheters that were inserted into a mass of tissue and used inflatable devices to expand perpendicular to the axis of the cannula. This created a working space when the distal end of the cannula expanded and caused separation along natural tissue planes for a substantial distance.
A surgical balloon dissector and method of use is disclosed in U.S. Pat. No. 5,496,345, to Kieturakis et al. This device provides for an expansible tunneling apparatus that creates an anatomic work space in a body mass. It is comprised of a tubular member with a rigid tunneling shaft having a blunt tipped obturator for tunneling through tissue to a desired location for dissection. The device contains a non-elastomeric balloon designed in the shape of a mantaray. This balloon on the distal end of the shaft is positioned in the preferred embodiment behind the inguinal region in the pre-peritoneal space after being introduced through an incision at the umbilicus.
In Johnson et al., U.S. Pat. No. 5,258,026, Johnson embellished Bonutti's work by describing a method for dissection using a tissue expander. He described use of a hollow endotube with a bullet shaped obturator that is used to tunnel to a desired location between skin and subcutaneous fat, skin and bone, skin and muscle or skin and fascia. The endotube is then used to deliver a tissue expander to the location which is then expanded to create spaces, cavities, or pockets in the body. He recommends overfilling the inflatable hollow member by 50%. The preferred embodiment of this method is a breast augmentation performed through an umbilical incision.
Johnson is still limited to creating spaces based on the dimensions of the device, even when the device was “overfilled by 50%”. Johnson was also imprecise in the tunneling of the endotube and positioning of the inflatable dissector. Its method lacked a sophisticated understanding of soft tissue anatomy and implied that it is practical and possible to create a dissection space at any desired location or plane of tissue. This is in fact not the case. For instance, it is not possible to perform minimally invasive blunt dissection with an inflatable device within the subcutaneous fat as Johnson claims. This is because of the existence of anatomic entities named “vertical cutaneous ligaments” which run up vertically from superficial fascia (which is in the horizontal plane) to the skin. This anatomic construct is analogous to a honey comb filled with honey, where the fat is the honey and the comb is the fascia and ligaments. Dissection in this natural plane (i.e. the subcutaneous plane) can only be performed with sharp dissection, or a constant combination of sharp and blunt dissection as in face lift surgery. This is because the vertical cutaneous ligaments cross the horizontal subcutaneous plane and resist blunt dissection.
In Rehnke, U.S. Pat. No. 6,055,989, fascial cleft surgery was first disclosed. A fascial cleft is an anatomic potential space between layers of fascia throughout the body with defined limits or boundaries, much like the peritoneal cavity. Fascial cleft surgery enables minimally invasive endoscopic surgery outside the peritoneal cavity in all regions of the body. Fascial cleft surgery not only respects the soft tissue anatomic layers and boundaries but takes full advantage of their existence. Unlike the peritoneal cavity, in laparoscopy, the potential space between layers of fascia has more cohesion and can not be separated into a true working space by CO2 gas insufflation. A specialized dissection instrument is required. The present invention relates to a specialized surgical instrument for use in fascial cleft surgery.
The patent to Bonutti, U.S. Pat. No. 5,163,949, discloses the use of cannulas to tunnel through a body mass indiscriminately and CREATES a work space in unspecified natural planes. The surgical apparatus comprising the present invention for use in fascial cleft surgery for tissue dissection utilizes a balloon device to perform the function of tissue dissection in a minimally invasive manner. The inflatable device of the Bonutti apparatus determines the size of the work space and retracts tissue based on the construct of the device shape. This method does nothing to delineate the size or boundaries of an underlying anatomic space. Bonutti's method relies on the design of the instrument rather than the inherent anatomic design of the body to create a space.
The surgical apparatus comprising the present invention uses open dissection, through a small incision, to a specific anatomic cleft between layers of known named fascia to enter a particular fascial cleft, which is analogous to the peritoneal cavity in laparoscopy. The inflatable device comprising the present invention, which has no predetermined inflated fixed shape or dimensions, is delivered into the fascial cleft without any tunneling through layers of tissue. The inflatable balloon apparatus of the present invention is designed to fail before achieving pressures that would destroy the anatomic boundaries of the fascial cleft. The pressure generated by the expansion of the device is weaker than the integrity of the fascia and the points of fusion between the two layers of fascia. The working space is not created, it is demonstrated. This is a fundamental difference in philosophy of dissection which requires a distinct difference in design and use of the instrument.
U.S. Pat. No. 5,496,345, to Kieturakis et al. discloses a device used for practicing a method of dissection. The only anatomic distinction made is in regard to the preperitoneal space in the preferred embodiment of inguinal hernia repair. It also creates a work space of dimensions that follow the design of the device rather than demonstrate existing anatomic spaces. The patent teaches a “balloon is formed of a non-elastomeric material; it is a volume-limited balloon to prevent overexpansion.” This reflects a fundamental departure from the philosophy regarding minimally invasive soft tissue dissection. The shape of the Kieturakis device has a non-elastic balloon of designed dimensions that creates a work space according to its fixed size. This is undesirable in the '989 Rehnke method of fascial cleft surgery. The present invention requires an elastic device which expands until it reaches the anatomic limits of the fascial cleft.
The Kieturakis device is made of a hollow tube with a rigid shaft with a hemispherical or ellipsoidal obturator at the end, designed to tunnel through tissue. This sort of straight rigid shaft with a bullet shaped obturator is highly undesirable if one wants to keep the device within a specific anatomic cleft during introduction of the inflatable member. The Present invention comprises a flat, beveled spoonbill distal end with a malleable end ideally suited for inserting the inflatable device of the present invention into a fascial cleft of curvilinear proportions without straying from that space. The Kieturakis device with its rigid shaft and obturator is prone to tunneling out of a desired fascial cleft.
In Johnson et al., U.S. Pat. No. 5,258,026, augmentation is disclosed wherein the surgery is performed through an umbilical incision. Johnson teaches the use of a hollow endotube with a bullet shaped nose piece for tunneling from a remote incision to a desired location for creation of a space, cavity, or pocket. This method of dissection relates to dissection of soft tissues in various regions within subcutaneous fat, between skin and bone, skin and muscle, or skin and fascia. It also describes dissection between fat and bone, fat and muscle fat and fascia and peritoneum and fascia; including between tissue and: bladder, nerves, blood vessels and muscle. This intrusive approach to invasive dissection generally disregards human anatomy. It is a method groping in anatomic darkness, hoping to hit an undefined mark. The use of a penetrating obturator for tunneling has the same design drawbacks of the Kieturakis device. The expander or prosthesis that is inflated to “overfilling . . . by about 50%”, relates to breast implants and tissue expanders. Thus this method patent advocates use of relatively inelastic prostheses that are “overfilled” to create a pocket; as apposed to the present invention device which is completely elastic and follows the design of the anatomic space and is stopped by the anatomic boundaries of the fascial cleft, rather than the point 50% beyond a prescribed fill volume.
Young, U.S. Pat. No. 5,871,497, teaches a device for dissecting along natural tissue planes to create a tissue pocket to hold the device which is left in place to perform traditional tissue expansion over a long term (days and months). It uses a device with a rigid base to establish the footprint and orientation of the expansion effort. This sort of device clearly has no use in fascial cleft surgery.
Accordingly, there is a need for improved surgical apparatus for use in fascial cleft surgery for minimally invasive surgical dissection to overcome the aforementioned disadvantages in the prior art.
The use of surgical dissection tools of known designs and configurations is known in the prior art. More specifically, balloon disectors of known designs and configurations heretofore devised and utilized for the purpose of surgical dissection through known methods and apparatuses are known to consist basically of familiar, expected, and obvious structural configurations, notwithstanding the myriad of designs encompassed by the crowded prior art which has been developed for the fulfillment of countless objectives and requirements.
While these devices fulfill their respective, particular objectives and requirements, the aforementioned patents do not describe a surgical apparatus for use in fascial cleft surgery for tissue dissection wherein a balloon device performs the function of tissue dissection in a minimally invasive manner.
In this respect, surgical apparatus for use in fascial cleft surgery for tissue dissection according to the present invention substantially departs from the conventional concepts and designs of the prior art, and in doing so provides an apparatus primarily developed for the purpose of utilizing a balloon device for performing the function of tissue dissection in a minimally invasive manner.
Therefore, it can be appreciated that there exists a continuing need for a new and improved surgical apparatus for use in fascial cleft surgery for tissue dissection which can be used for performing the function of tissue dissection in a minimally invasive manner. In this regard, the present invention substantially fulfills this need.